1. Field of Invention
The invention relates to an electrophotographic image forming apparatus and a processing device used in the electrophotographic image forming apparatus.
2. Description of Related Art
An image forming apparatus, such as a laser-beam printer, is detachably attached with a processing device, which includes a photosensitive drum onto which an electrostatic latent image is formed, a developing roller for holding toner particles to be adhered onto the electrostatic latent image formed on the photosensitive drum, and a transfer roller for transferring a toner image, which is formed by adhering the toner particles to the latent image, onto a sheet.
In the processing device, toner particles held by the developing roller adhere to an electrostatic latent image formed on a surface of the photosensitive drum, thereby forming a toner image on the surface of the photosensitive drum. The toner image formed on the surface of the photosensitive drum is then transferred onto a sheet passing between the photosensitive drum and the transfer roller. Thus, an image is formed on the sheet.
When the toner particles adhere to a sheet, contaminants or foreign substances may adhere to the surface of the photosensitive drum from the sheet. Japanese Laid-Open Patent Publication No. 61-121076 discloses a device provided with a cleaning blade which is in contact with a surface of a photosensitive body at all times in order to physically remove contaminants adhering to the photosensitive body.
Because the cleaning blade is in contact with the surface of the photosensitive body at all times, the surface of the photosensitive body may be damaged or scratched if the contacting force of the cleaning blade against the surface of the photosensitive body is too strong. However, if the contacting force is too weak, the contaminants cannot be adequately removed from the surface of the photosensitive body, resulting in degradation of an image quality.